Writable optical disk recording apparatus
US5353270A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Nov 23, 1992 |
| Grant date | Oct 4, 1994 |
| Priority date | — |
| Expiry date | Nov 23, 2012 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B20/182
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
The present invention is directed to a writable optical disk recording apparatus in which an output power of a laser beam is controlled even during a recording period. During a calibration mode, a reproduced (reflected) signal from a matrix circuit (12) is supplied to level hold circuits (37), (38). The level hold circuits (37), (38) are controlled at predetermined timings relative to recording EFM (eight-to-fourteen modulated) signals of bit lengths (3T) and (11T) under the control of a microcomputer (CPU) (31). Signals from the level hold circuits (37), (38) are supplied to a calculating circuit (39) which calculates, for example, a difference or ratio between the two signals. A calculated value is stored in a memory (40). The value stored in the memory (40) and a value newly calculated by the calculating circuit (39) during EFM data recording are compared with each other by a subtracting circuit (41). A compared output is selected by a switch (34) and then supplied through a subtracting circuit (35) to control a laser driver (3).
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.